1. Field of the Invention
This invention relates to an active headset for reducing the amount of external noise reaching the ear under noisy conditions, for example in an aircraft or other vehicle.
2. Background of the Invention
Such active headsets are well known and include a microphone in each earpiece for generating a signal representative of detected external noise and an earphone in each earpiece which propagates a noise cancellation signal generated by processing of the external noise representative signal produced by the microphone.
It is generally accepted that, due to time delay problems, only a given range of lower frequencies present in the external noise can be canceled.
Nevertheless, some users feel discomfort when wearing active headsets providing noise cancellation over the given frequency range, as they experience a feeling of pressure within the ears.
From U.S. Pat. No. 5,138,664 is known an active headset which includes a conventional variable gain amplifier interposed between the microphone and the loudspeaker, whereby the user can vary the peak amplitude of the noise cancellation signal. In the arrangement disclosed in this patent, however, variation of the peak amplitude of the noise cancellation spectrum is accompanied by marked variation in the total range of frequencies over which noise reduction is effective.
There is thus an unmet need in the art to provide an active headset that can cancel external noise in both the higher and lower frequency range while reducing a users feeling of pressure within the ears.